Goa'uld Buster missile
From The Stargate Omnipedia
Twin weapons conceived by the Pentagon and Major Samuels as a preemptive strike against two Goa'uld Ha'tak motherships which settled into Earth orbit shortly following the reactivation of the S.G.C. Each weapon was a naquadah-enhanced Mark 12-A warhead yielding a potential excess of one thousand megatons. Impacting against Goa'uld Ha'tak shielding, the weapons proved to be entirely ineffective.
KEY EPISODE
The Serpent's Lair - Arrogant in his plan of success, Samuels is crushed when he realizes the Goa'uld Busters have no hope of saving Earth.